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Hibernation in an antarctic fish: on ice for winter.

Campbell HA, Fraser KP, Bishop CM, Peck LS, Egginton S - PLoS ONE (2008)

Bottom Line: This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature.Whilst inactive during winter, N. coriiceps displayed a very low f(H), reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer.This study demonstrates that at least some fish species can enter a dormant state similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, University of Birmingham, Edgbaston, Birmingham, England. dr.hamish.campbell@gmail.com

ABSTRACT
Active metabolic suppression in anticipation of winter conditions has been demonstrated in species of mammals, birds, reptiles and amphibians, but not fish. This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature. However, the Antarctic fish (Notothenia coriiceps) is unusual because it undergoes winter metabolic suppression irrespective of water temperature. We assessed the seasonal ecological strategy by monitoring swimming activity, growth, feeding and heart rate (f(H)) in N. coriiceps as they free-ranged within sub-zero waters. The metabolic rate of wild fish was extrapolated from f(H )recordings, from oxygen consumption calibrations established in the laboratory prior to fish release. Throughout the summer months N. coriiceps spent a considerable proportion of its time foraging, resulting in a growth rate (G(w)) of 0.18 +/- 0.2% day(-1). In contrast, during winter much of the time was spent sedentary within a refuge and fish showed a net loss in G(w) (-0.05 +/- 0.05% day(-1)). Whilst inactive during winter, N. coriiceps displayed a very low f(H), reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer. In a similar manner to other hibernating species, dormancy was interrupted with periodic arousals. These arousals, which lasted a few hours, occurred every 4-12 days. During arousal activity, f(H) and metabolism increased to summer levels. This endogenous suppression and activation of metabolic processes, independent of body temperature, demonstrates that N. coriiceps were effectively 'putting themselves on ice' during winter months until food resources improved. This study demonstrates that at least some fish species can enter a dormant state similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits.

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The free-ranging metabolic rate of N. coriiceps.The mean monthly MO2 of wild N. coriiceps (black line, n = 6) was extrapolated from continual field recordings of fH using the equation given in Fig. 3. Water temperature was measured by an onboard temperature sensor (red).
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pone-0001743-g004: The free-ranging metabolic rate of N. coriiceps.The mean monthly MO2 of wild N. coriiceps (black line, n = 6) was extrapolated from continual field recordings of fH using the equation given in Fig. 3. Water temperature was measured by an onboard temperature sensor (red).

Mentions: The mean fH recorded from fish inhabiting sea-cages during February was 25.2±1.2 min−1 and the estimated field MO2 for this month was 3.59±0.78 mg O2 100 g−1 h−1 (Fig. 4). Between February and April there was a 23% decline in fH and therefore MO2. The fall in sea water temperature to the yearly low (−1.8±0.02°C) occurred in mid-April, and thus succeeded the decline in N. coriiceps metabolism. Between June and October fH showed little variability and remained around 11±0.8 min−1 with a calculated metabolic rate of 1.48 mg O2 100 g−1 h−1. Consequently, summer and winter metabolism differed by 58%. During November and December fH and water temperature steadily increased, however by mid-December water temperatures reached the summer maximum of 0.7±0.02°C whilst fH and MO2 continued to rise through December until February.


Hibernation in an antarctic fish: on ice for winter.

Campbell HA, Fraser KP, Bishop CM, Peck LS, Egginton S - PLoS ONE (2008)

The free-ranging metabolic rate of N. coriiceps.The mean monthly MO2 of wild N. coriiceps (black line, n = 6) was extrapolated from continual field recordings of fH using the equation given in Fig. 3. Water temperature was measured by an onboard temperature sensor (red).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2254195&req=5

pone-0001743-g004: The free-ranging metabolic rate of N. coriiceps.The mean monthly MO2 of wild N. coriiceps (black line, n = 6) was extrapolated from continual field recordings of fH using the equation given in Fig. 3. Water temperature was measured by an onboard temperature sensor (red).
Mentions: The mean fH recorded from fish inhabiting sea-cages during February was 25.2±1.2 min−1 and the estimated field MO2 for this month was 3.59±0.78 mg O2 100 g−1 h−1 (Fig. 4). Between February and April there was a 23% decline in fH and therefore MO2. The fall in sea water temperature to the yearly low (−1.8±0.02°C) occurred in mid-April, and thus succeeded the decline in N. coriiceps metabolism. Between June and October fH showed little variability and remained around 11±0.8 min−1 with a calculated metabolic rate of 1.48 mg O2 100 g−1 h−1. Consequently, summer and winter metabolism differed by 58%. During November and December fH and water temperature steadily increased, however by mid-December water temperatures reached the summer maximum of 0.7±0.02°C whilst fH and MO2 continued to rise through December until February.

Bottom Line: This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature.Whilst inactive during winter, N. coriiceps displayed a very low f(H), reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer.This study demonstrates that at least some fish species can enter a dormant state similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, University of Birmingham, Edgbaston, Birmingham, England. dr.hamish.campbell@gmail.com

ABSTRACT
Active metabolic suppression in anticipation of winter conditions has been demonstrated in species of mammals, birds, reptiles and amphibians, but not fish. This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature. However, the Antarctic fish (Notothenia coriiceps) is unusual because it undergoes winter metabolic suppression irrespective of water temperature. We assessed the seasonal ecological strategy by monitoring swimming activity, growth, feeding and heart rate (f(H)) in N. coriiceps as they free-ranged within sub-zero waters. The metabolic rate of wild fish was extrapolated from f(H )recordings, from oxygen consumption calibrations established in the laboratory prior to fish release. Throughout the summer months N. coriiceps spent a considerable proportion of its time foraging, resulting in a growth rate (G(w)) of 0.18 +/- 0.2% day(-1). In contrast, during winter much of the time was spent sedentary within a refuge and fish showed a net loss in G(w) (-0.05 +/- 0.05% day(-1)). Whilst inactive during winter, N. coriiceps displayed a very low f(H), reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer. In a similar manner to other hibernating species, dormancy was interrupted with periodic arousals. These arousals, which lasted a few hours, occurred every 4-12 days. During arousal activity, f(H) and metabolism increased to summer levels. This endogenous suppression and activation of metabolic processes, independent of body temperature, demonstrates that N. coriiceps were effectively 'putting themselves on ice' during winter months until food resources improved. This study demonstrates that at least some fish species can enter a dormant state similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits.

Show MeSH
Related in: MedlinePlus